Selenium and Toxicological Aspects: Cytotoxicity, Cellular Bioavailability, and Biotransformation of Se Species

This book chapter reviews the current literature regarding the cytotoxicity, bioavailability, and biotransformation of the diet-relevant selenium species selenite, Se-methylselenocysteine, selenomethionine, as well as selenium excretion metabolites trimethylselenonium and selenosugar 1 in cultured mammalian cells. Limitations as well as potentialities are summarized. In case of no cytotoxic response, it is needful to ensure that the respective selenium species are bioavailable to the respective cellular models before concluding that they exert no toxicity in vitro. To further understand selenium species metabolism in vitro but also to unveil potential causes for the differing cytotoxic potencies of selenium species, a combined quantification of free selenium species in cell lysates and total cellular selenium quantification is recommended. Finally, in vitro approaches are reviewed that helped to identify new selenium species metabolites and thus contributed to our understanding of the role of these metabolites in the detoxification or toxification of selenium species.